Light emitting diode (LED) lighting systems are becoming more prevalent as replacements for existing lighting systems. LEDs are an example of solid state lighting and have advantages over traditional lighting solutions such as incandescent and fluorescent lighting because they use less energy, are more durable, operate longer, can be combined in multi-color arrays that can be controlled to deliver virtually any color light, and contain no lead or mercury.
In many applications, one or more LED dies (or chips) are mounted within an LED package or on an LED module, which may make up part of a lighting system, a light fixture, lighting unit, lamp, “light bulb” or more simply a “bulb,” which includes one or more power supplies to power the LEDs. An LED bulb may be made with a form factor that allows it to replace a standard threaded incandescent bulb, or any of various types of fluorescent lamps. Alternatively, and LED lamp or fixture may be made in the form of a fixture to be used in place of or instead of a standard incandescent or fluorescent fixture.
LED fixtures and lamps often include optical elements external to the LED modules themselves. Such optical elements may allow for diffusion, localized mixing of colors, collimation of light, and/or beam shaping. Optical elements may include reflectors and/or, lenses. Lenses may be of glass or plastic and as examples may take the form of lens plates, total internal reflection (TIR) elements, or more traditional circular, concave or convex lenses.